Counting mechanism



Aug. 29, 1944. c BLANCHA 2,356,9143

COUNTING MECHANISM Filed May 1, 1943 2 Sheets-Sheet l 3nnentor Felt[.Dlane/lw @M (ltt omeg 1944- F. c. BLANCHA 2,356,914

COUNTING MECHANISM Fild May 1, 194:: 2 Sheets-Sheet 2 X Z ISnnentor ciawGttorncg Patented Aug. 29, 1944 COUNTING MECHANISM Felix c. Blanch...Mama, 1%., minor to Radio Corporation of A merica, a corporation ofDelaware Application May 1, 1943, Serial No. 485,396

6 Claims.

This invention relates to an improved dial mechanism for counting andindicating the number .of revolutions and fractions of a revolution of ashaft, such, for example, as the tuning shaft of a radio transmitter orthe like.

The principal object of the present invention is to provide a reliableand trouble-free counting mechanism, and one nevertheless characterizedby the simplicity and economy of its parts.

Another object of the present invention is to provide an inexpensivemechanical movement for counting devices and the like, and one whereinthe driving and driven elements are at all times in positive mechanicalengagement, whereby slippage and uncounted cycles are obviated.

- Still another object of the invention is to provide an improved pluralscale indicator wherein the setting of the main scale remains fixedthroughout the greater portion (say, 270) of each operating cycle of theauxiliary or fractional revolution scale," whereby a rapid and accuratereading of both scales is ensured.

Certain details of construction together with other objects andadvantages will be apparent and the invention itself will be bestunderstood by a reference to the following specification and to theaccompanying drawings, wherein:

Fig 1 is a front elevational view of a plural scale counting deviceincorporating the invention,

Fig. 2 is a side elevation partly in section showing the counter appliedto the tuning shaft of a radio apparatus,

Fig, 3 is a front elevation of the device of Figs. 1 and 2 with the knoband central scale removed to reveal its drive mechanism,

Fig. 4 is an exploded view, partly in section, showing the several partsof the device,

Fig. 5 is a front elevational view of the internal gear upon which themain scale is marked,

Fig. 6 is a sectional view taken on the line 6'6 of Fig. 5 and Fig. 7 isa sectional view taken on the line l-l of Fig. 5,

, Fig. 8 is a front elevationalview, with the gear of Fig. 5 removed,and revealing the gear support and the cam actuated rocker by which thepartsinallflgu s.

The plural scale counter or dial which has been selected forillustration comprises a main scale I and an auxiliary scale 2 which areassembled, in

a manner later described, upon a backing plate 3 which is shown in Fig.2 attached by means of screws 4, to the front panel 5 of a radio chassisor cabinet 6. A knob l which forms part of the dial assembly is attachedby means of a set screw 8 to the free end of a control shaft 9 whichextends through a suitable bushing or aperture in in the front panel 5,

The tuning device controlled by the shaft 9 is not here shown but it maycomprise an inductance coil and trolley arrangement similar to the oneshown, by way of example, in U. S. Patent No. 2,178,221to F. C. B1ancha.In this event the plural scale dial here illustrated operates to showthe number of full and fractional revolutions of the tuning shaftrequired to move the trolley from its zero setting, at one end of thecoil, to a position whereat the desired variationin inductance isachieved. I

The fractional revolutions of the shaft 9 are indicated by the auxiliarydecimal scale 2 which, as shown in Fig. 4, may comprise a skirt on theinner end of the control knob l. The full revolutions are indicated onthe surrounding main-scale I, which is rotated, in a manner laterdescribed, by means of a cam ii and a cam follower or rocker i2 arrangedon and about the tuning shaft 9, The indicia on both the main scale Iand on the auxiliary scale 2 are read in conjunction with a stationarypointer or referenc line l3 marked on an immovable clamping ring llbetween the twoscales.

As shown more clearly in Fig. 5, the main'scale I is marked on theexposed face of an annulus l5 which is provided with gear teeth'ili onits'inner perimeter. This internal gear I5 is supported in-' ternally bya split ring" comprising a pair'fof spaced apart, smooth surfaced,arcuate pi'o which the control shaft 9 extends.

As previously indicated, the scale bearing an: 5 nulus or gear I5 isrotated on it bi-part internal V I8, by means of a cam-actuated rockeri2. The cam II that moves the rocker l2 1 support I'l,

comprises a circular member mounted oil-center on the shaft 9, and therocker I! has a centrallylocated aperture lZa within which the said camhas abearing-fit. shaft 9 the cam ll tends to impart an epicy-clicmovement to the rocker l2. However, as will hereinafter more fullyappear, the unique shape Thus, upon rotation of the I and arrangement ofthe rocker I2 causes the driving force, which is imparted thereto by thecam i I, to be converted into an eccentric, reciproeatin or "rocking"movement which serves to drive the gear l in discrete steps instead ofwith the continuous motion characteristic of a true epicyclic movement.

The construction required to provide the described movement is shown inFig. 3: The rocker i2 is provided with a pair of outwardlyextendoppositely located spokes or arms I2b and He, ach of whichterminates in a tooth or finger I2d d 52c, respectively. The diameter ofthe better as measured along its arms is slightly less hen the rootdiameter of the gear I5 and preferly corresponds to the pitch' diameterof the ar I5, minus the throw of the cam II. Thus,

hould the finger .lZe on the arm 52c fall in the lnterdental spacebetween two 01' the gear teeth IS, the opposite finger Md on the arm I2bwill at the same time be drawn out of engagement with the teeth at theopposite side of the gear I5.

It will be observed upon inspection of Figs. 3 and 8 that the twodiametrically opposite spaces m and 11 between the adjacent ends of thearcuate risers ii and I8, and between which the ends of the rocker armsI22; and I20 are confined, respectively, are not of the same dimensions.That is to say, the upper space m is here shown as slightly wider thanthree of the gear teeth I6, while the lower space 11 is spanned by buttwo teeth. The maximum width of the lower rocker arm I20 correspondssubstantially to the width of the space n within which it is confined;hence, it cannot move either in a clockwise or counter-clockwisedirection, but only radially, into and out of engagement with the geartooth with which it is in register. In undergoing such movement,however, its tapered sides permit of its being tilted slightly either tothe left or to the right, as on a pivot. The upper rocker arm IZb, onthe other hand, is not limited to a simple reciprocating movement butmay be moved in a clockwise or in counterclockwise direction (about Heas a pivot) within the relatively wider space 111 defined by the upperends of the cam supports I1 and I8.

Before proceeding with a detailed description of how the cam-actuatedrocker I2 drives the scale-bearing internal gear I5, attention is calledto the fact that the rocker is maintained upon the cam II by means ofthe clamping ring I4. This ring I4 fits within a recess, provided forthe purpose, in the front surface of the gear l5 and is secured to theback plate 3 by means of two screws I9 (Figl 9) which entercomplementarily threaded holes 20 (Fig. 8) in the risers I! and I8 uponwhich the gear l5 rotates.

In a conventional counting mechanism wherein the relative movementbetween the scale and the pointer comprises a continuous movement thereis a very real chance that the operator may misread the scale when thepointer is part way between two adjacent indicia. -'I'his hazard isgreatly reduced when the counter of the present invention is employedsince the main scale I remains stationary throughout 270 of theoperating cycle and, during the last quarter-cycle, moves very rapidlyto a position whereat the next indicia is in register with the pointerI3. Why this is so will be apparent from the following analysis of acomplete operating cycle, as pictured in Figs. 10 to 13, inclusive.These drawings are marked with two reference lines W-X,

Y-Z which intersect at right angles to indicate four quarter-cycles ofmovement.

In Fig. 10 the rocker I2 is shown in a position ,whereat it has alreadyadvanced the main scale from its zero (0) gradation to the first decimalmarking, I. In this position the maximum rise of the cam II lies alongthe line Y-Z and the finger I2d on the end of the upper rocker arm no isstill fully engaged, but ready to be withdrawn from engagement, with thegear teeth during the next of rotation of the control shaft 9.

In Fig. 11 the cam II has been rotated (in a clockwise direction) 90from the position shown in Fig. 10. It will be noted that the indicia(I) on the scale I remains in register with the pointer i3. Here therise of the cam lies along the line W-X. At this moment the finger i2don the end of the upper rocker arm in; has been withdrawn from the gearteeth I5 and the finger l2c on the lower arm IZc has dropped intoengagement with the gear teeth adjacent thereto.

In Fig. 12 the cam H has been rotated, in the same direction, 90 fromthe position shown in Fig. 11 and its maximum rise lies along the lineY--Z. Here again it will be noted that the pointer I3 still is inregister with the mark I on the scale I. During this 90 rotation of theshaft 9 the lower finger I2e remains in engagement with the gear teethI6 and the rocker has been pivoted to the left so that its upper fingerI2d is ready to engage the tooth next succeeding the one from which itwas disengaged in Fig. 11.

In Fig. 13 the shaft 9 has been rotated 270 from the position shown inFig. 10 and the pointer l3 still remains in register with the firstscale mark (I). During this last 90 rotation. here shown, the cam II hasbeen moved to a position whereat its maximum rise is along the line X-W,and the rocker I2 has been moved by the cam to a position whereat itslower finger He has been disengaged and its upper finger l2d moved intodriving relation with the interdental space with which it is in registerin Fig. 12. It will now be apparent that it is only during the next 90of rotation (shown in Fig. 10) that the scale per se rotates, to bringits next mark (2) into register with the pointer.

Attention is called to the fact that at all times during the abovedescribed 360 cycle of rotation, one or the other of the fingers IM orMe is positively engaged by the teeth IS on the gear I5. Hence, theshaft 9 cannot be rotated 360 without such full cycle of rotation beingevidenced by the indicia of the main scale I. Since the auxiliary scale2 is coupled directly to the shaft 9, a fractional revolution will beaccurately indicated on that scale.

One very real advantage of the device of the present invention remainsto be pointed out. In a conventional epicyclic movement employingdriving and driven gear wheels, all of the teeth on both wheels are usedduring each revolution; thus, when it is desired to provide anindication of the limit of movement of the controlled device it isnecessary to provide the device with an auxiliary stop mechanism. Sincethe mechanism of the present invention dispenses with the use of a.driving gear and employs but a single drivin'g finger, any tooth on thedriven gear I5 may be suitably blocked to provide a stop for the shaft9. Thus, as shown in Figs. 5, 6 and 7, two teeth on the driven gear are"blocked as indicated at 20, 2| to limit the rotation of the a typicalembodiment and application of the invention should be interpreted asillustrative and not in a limiting sense except as required by the priorart and by the spirit of the appended claims.

I claim as my invention:

1. A device of the character described comprising a base, a split ringon said base, an internal gear supported on its inner perimeter on saidsplit ring for rotation, a cam and a cam follower mounted for eccentricmovement adjacent to the center of said split ring, said cam followerhaving an arm which extends into said split and of a length sufllcientto be moved into and out of driving engagement with the portion of saidgear which lies adjacent to said split when said cam follower isactuated by said cam, and means for actuating said cam. I

2. The invention as set forth in claim 1 and wherein said split ring isprovided with a second diametrically opposite split and said camfollower is provided with a second oppositely extending arm whichterminates within said second split, the overall length of said camfollower as measured along said arms being such that saidsecond arm isin engagement with said gear when said first mentioned arm isdisengaged, whereby undesired rotation of said gear is prevented.

3. A device of the character described comprising a base, a pair ofopposed arcuate mem- 'bers arranged about a common center on said base,an internal gear supported on its inner perimeter on said arcuatemembers for rotation, the ends of said arcuate members being spaced fromeach other at circumferentially spaced points to provide twodiametrically opposite spaces between the adjacent of said ends, a camfollower comprising a pair of oppositely extendin'g arms of an overalllength slightly less than the root diameter of said internal gear, saidarms terminating respectively within said oppositely located spaces andeach adapted to engage said gear, and cam means'for imparting areciprocating movement to said cam follower whereby the oppositelyextending arms thereof are presented, sequentially, to the portions ofsaid gear which lie within the boundaries of said spaces.

4. The invention as set forth in claim 3 and wherein each of said camfollower arms terminates in a projection whichis adapted to be enteredinto and withdrawn from the interdental spaces on said gear when saidcam. follower is subjected to said reciprocating movement.

5. The invention as set forth in claim 3 and wherein the overall lengthof said cam follower corresponds substantially to the pitch diameter ofsaid gear, minus thethrow of said cam, whereby when said cam follower issubjected to said reciprocating movement at least one of said arms is atall times in engagement with said gear.

6. The invention as set forth in claim 3 and wherein one of saiddiametrically opposite spaces is of a width corresponding substantiallyto the width of the arm which moves therein, whereby the motion of saidarm within said space comprises, substantially, a reciprocating radialmovement.

max C. BLANCHA.

